Fill in the blanks :
i. The morphology of the chromosome is studied at ………..A………
ii. Recombination nodule appears at ………B………….stage of prophase - I
iii. ……….C………..induces polyploidy by inhibiting polymerisation of spindles.
iv. True reduction in number of chromosome occurs in ..........D.... stage.

Options

A. A - Anaphase , B - Pachytene
B. C - Mustard gas, D - Metaphase I
C. A - Prophase , C - Colchicine
D. B - Pachytene , D - Anaphase - I

Answer

To fill in the blanks in the provided statements, we will analyze each part step by step:

i. The morphology of the chromosome is studied at ………..A………
- The morphology of chromosomes, which includes their shape, size, and number, is best observed during the **Metaphase** stage of cell division. During this phase, chromosomes are highly condensed and aligned at the metaphase plate, making them easier to visualize.

**Answer for A: Metaphase**

ii. Recombination nodule appears at ………B………….stage of prophase - I
- Recombination nodules are structures that facilitate genetic recombination during meiosis. They appear during the **Pachytene** stage of Prophase I. This is the stage where homologous chromosomes are paired closely together, allowing for crossing over to occur.

**Answer for B: Pachytene**

iii. ……….C………..induces polyploidy by inhibiting polymerisation of spindles.
- The compound that induces polyploidy by inhibiting the polymerization of spindle fibers is **Colchicine**. Colchicine disrupts the formation of the spindle apparatus, preventing proper chromosome segregation during cell division.

**Answer for C: Colchicine**

iv. True reduction in number of chromosome occurs in ..........D.... stage.
- The true reduction in the number of chromosomes occurs during **Anaphase I** of meiosis. During this stage, homologous chromosomes are separated and pulled to opposite poles of the cell, effectively reducing the chromosome number by half.

**Answer for D: Anaphase I**

### Final Answers:
- A: Metaphase
- B: Pachytene
- C: Colchicine
- D: Anaphase I